Safety core insulator



A. O. AUSTIN SAFETY CORE INSULATOR Filed June 18, 1936 3 Sheets-Sheet 1g I T744750 to? 01F F4JP/c 2 I4 WWW TPEAT (aka a? mwmm / WNW IPE47E0 c020 0/? F4 a FIG 0a. 10, 1939. A, o, AUsTlN 2,175,336

SAFETY CORE INSULATOR Filed June 18, 1936 3 Sheets-Sheet 2 Fig.|6.

lNVENTOR 'mocwzi Oct. 10, 1939. O ug-rm 2,175,336

SAFETY CORE INSULATOR Filed June 18, 1936 3 Sheets-Sheet 3 Fig. l7.

Fig..l9.

INVENTOR Patented 0a. 10, 1939 UNlTED a STATES PATENT OFFICE SAFETY CODEINSULATOR Arthur 0. Austin, near Barherton, Ohio Application June 18,

4 Claims.

In the transmission of power and in the insulation 01' radio stationsthere is need for insulators of high strength and mechanicalreliability, and having good electrical properties. Desirable mechanicaland electrical properties may be obtained by making up an insulatorhaving an outer sleeve such as glass or porcelain which will withstandleakage current and weathering but which may carry little or nomechanical load, together with an internal member which sustains themechanical load particularly where this load is in tension. Insulatorsof this general type heretofore have been used but they are large andcostly, consequently their use is restricted. The previous methods ofgripping the internal tension member require rather large and costlyheads. -7 a One of the objects of my invention is to provide an improvedtype of construction which-simplifies the mechanical construction andreduces the size, weight and cost of the insulator.

vAnother object is toprovide a construction which will have improvedmechanical reliability.

Another object is to provide an improved tension member and method ofattaching same.

Other objects and advantages will appear from the followingspecification and will readily suggest themselves to those skilled inthe art..

. The invention is exemplified by the oombina tion and arrangement ofparts shown in the accompanying drawings and described in the followingspecificationand it, is more particularly pointed out in the appendedclaims.

In the drawings:

Figs. 1, 4 7, 8, 11, and are longitudinal sections of insulators showingdifi'erent embodiments of the present invention.

Figs. 2, 5, 9, 12, and on lines 2-2, 5-4, of Figs. 1, 4, 8, 11, and 20respectively.

21 are transverse sections Fig. 3 is a fragmentary longitudinal sectionat right angles to the section shown 11112;. 1.

Fig. 6 is atransverse section on 1 H oi Fig. 4 but showing the additionof a filler.

Fig. 10 is a side elevation of apparatus for forming reinforcing links.

Figs. 13, 15, 1'7, and 19 are elevations, partly in section showingother forms of the invention.

- Fig. 14 is a plan view of Fig...l3.-

Figs. 16 and 23 are elevations, respectively, of other forms of theinvention.

Fig. 18 is a transverse section on line Il-IB of Fig. 17.

Fig. 22 is a transverse section, similar to Fig. 21, of a modificationof the invention.

a-s, 12-12, snarl-2|,-

1936, Serial No. 85,948

Fig. 24 is a transverse section of the member I28 on line 24-24 in Fig.23. v

Fig. 25 is a transverse section of the member I29 on line 25-2i in Fig.23.

Fig. 26 is a transverse section, similar to Figs. 5 24 and 25, of amodification of member I29 in Fig. 23.

In the form of the invention shown in Figs. 1, 2 and 3 the outer jacketIII is held between heads II having attaching ears I2. Gaskets II arepro- 10 vided so that oil or other insulating medium can be retainedwithin the sleeve or member III so as to prevent electrical dischargeunder operating conditions. An insulating link Il is made in the form ofa fiat loop. Flat shaped eyes I! l are inserted in a slot I6, and abearing yoke or keeper IT is inserted in the eye IS. The yoke hasprojecting lugs I8 which engage the edges of the link H. The innersurface of the link bears upon the rounded edge I9 of the member 20 I1,which is shown in section in Fig. 3. The eye members I! are enlarged attheir inner ends as shown at 20 in order to provide increased bearing 7area between the member I5 and thegyoke member II. The slots I8 are madelong enough so 26 that the member II with the enlarged portion can beshoved thru the slot. If desired two separate links can be used althoughthe single unit is preferable as it tends to prevent disenga i oi. theparts. The space between the internal ele- 30 ments and the sleeve isfilled with oil or insulating compound, suflicient space being allowedonly for the expansion of the material unless separate expansionchambers are provided.

In Fig. 1 the heads II are screwed onto the 36 studs 2|. This places thesleeve II in compression and the insulating link I4 in tension. Ingeneral sufiicient tension is applied on the central member so thatunder working conditions the seal between the insulating sleeve I. andthe 40 heads II will not be broken. In other words the insulators arepreloaded. This has some very great advantages as cement joints andpacldng glands are eliminated. This greatly reduces the size and cost ofthe insulator and tends to eliminate mechanical stress which may causedamage to the insulating sleeve ll, brought about by the largedifierence in the linear coefllcient ofexpansion between theinsulatingsleeve II and the metal for changes in temperature. Due to the practicalelimination of this so-called thermal stress, materials such as copper,bronze or aluminum which have higher linear coemcients of expansion thaniron or steel can be used without increasing the danger of cracking ofthe insulatl6 ing member, which usually is porcelain or glass having arelatively low linear coeflicient of expansion.

In Fig. 1 a construction is used which permits of the use of aninsulating link having a cross section which is a large percentage ofthe cross section of the opening in the insulating sleeve. Insulatingsleeves are not necessarily restricted to circular types, but these arethe most easily constructed and generally are stronger mechanically thanmembers having rectangular cross sections. Where the cross section ofthe insulating link constitutes a large percentage oi the cross sectionof the opening in the insulating sleeve, the size and cost of the lattercan be materially decreased.

Where the space 22 between the insulating link and the insulating sleeveis relatively small, the volume of oil or insulating compound isreduced. Since most insulating compounds have a relatively largevolumetric coefiicient of expansion for changes in temperature, thissmall volume has the advantage that reduced space can be provided forthe expansion of the filling medium for the higher temperatures. Wherethis volume is small expansion chambers may be omitted or the length ofthe insulating links with respect to the sleeve may be increased. Whereappreciable space is required particularly for long insulators theinsulating links may not be covered by the insulating medium.- Whenworking at high voltages this may subject the insulating link toelectrical discharges. In order to prevent this shields 23 which areelectrically connected to the terminals thru the draw bolts l5 and yokesI! are provided. Other forms of shielding may be used which will permita lowered level of the filling medium without exposing the insulatinglinks to a discharge.

Where it is not necessary to use as large a cross section of the link asthe interior of the insulating member will permit, other types ofconstruction may be used. A construction of this kind is shown in Fig.4.

In Fig. 4 the insulating link 24 has a much smaller cross sectionrelative to the opening in the sleeve 25 than in Fig. 1. A cross sectionthru the center of the insulator is shown in Fig. 5. The space 26between the insulating link 24 and the insulating sleeve 25 isrelatively large. In Fig. 4 one end of the insulating link 24 is held bya U shaped bolt 21. The other end is held by a pin 28 which passes thrucars 23 which are a part of the head 33. The reaction between theinsulating link 24 and the insulating sleeve 25 is obtained bytightening the nuts 3| which bear upon the head 32. Load is applied tothe insulator by means of the eye 33 and clevis 34.

Where it is desired to reduce the volume of the insulating medium usedto fill the space between the insulating link and the sleeve, this maybe accomplished by suitable insulating fillers. One method ofconstruction is shown in Fig. 6. In Fig. 6 sectional pieces ofinsulation 35 and 36 are placed in the slot formed by the two sides ofthe link 24. By making the pieces with suitable interlocking projectionsthey will be held in place while the link mechanism is passed thru theinsulating sleeve 25. It is readily seen that these filling members willdisplacea large portion of the filling liquid in'the space between theinsulating links and the insulating tube. The amount of filling mediummay be further reduced by filling in any remaining space 31 with sand orinsulating material. By using methods of this kind the amount of fillingmedium may be greatly reduced so that the space required for expansionwill be exceedingly small. This is important where an expensive fillingmaterial is used or where the insulator is operating in a horizontal ornearly horizontal position and it is desired to eliminate a space whichmay permit of a discharge inside the tube When the insulator issubjected to a high voltage or to lightning.

This method of reducing the volume of filling material is applicable topractically all of the various types of insulators shown in the severalfigures. In some cases the filling pieces and material can be used toprevent internal discharge and increase the internal breakdown voltage.This is valuable where the length of the insulating sleeve is so shortthat the links which engage the insulating member are brought neartogether.

Fig. 7 shows a further modification of the insulator shown in Fig. 1.The method of gripping the insulating link is the same. However, theinsulating sleeve 38 bears against a terminal 39 at one end andexpansion chamber 40 at the other. The expansion chamber allows forvariations in volume of the filling medium. The construction has theadvantage that the initial or preloading of the insulator can beapplied'very easily and determined with a high degree of accuracy. Theinsulating link 4| with the tension eye 42 is passed thru the insulatingsleeve 38 and the expansion chamber 40. Ground joints 43 may be coatedtoinsure a tight seal betweenthe insulating sleeve and the adjacentterminal members when they are under pressure. If desired gaskets may beapplied at this point. The draw eye 42 is provided with a long threadedstud 44 and a nut 45. By using a suitable mechanism which will draw thestud 44 outward thru the top of the expansion chamber 40 it is possibleto subject the link 4| to tension and set up the desired pressurebetween the insulating sleeve 33 and the terminals at the joint 43. Itis evident that this may be readily accomplished by attaching suitablepulling means to the end of the stud 44 and applying an equivalentpressure against the top of the expansion chamber 40, the eye member 46being removed. When the necessary stress is set up the nut 45 may beseated against the top of the expansion chamber. This nut can be used toform a tight seal. The resiliency or deformation in the variousmechanical parts will maintain the pressure under operating conditions.

After the insulator is assembled the eye member 46 may be screwed ontothe stud 44. A filling plug 41 is provided so that the insulating medium43 may be poured into the insulator. The expansion chamber is providedwith a weather shed or shield 49 which deflects drip water and reducesthe leakage loss 01' the insulator under storm conditions. This memberalso provides an electrostatic shield.

In Fig. 7 the insulator is suitable where it is operating in a verticalor inclined position. Where the insulator is operating in a horizontalposition it generally is advisable to place the expansion chamber abovethe insulator. An arrangement of this kind is shown in Fig. 8. Theexpansion chamber 50 is provided with an opening 5| which connects withthe interior of the insulator. Since the expansion chamber is 'wellabove the insulating sleeve 52, the space between the insulating links53 and 54 and the insulating sleeve can be maintained full of theinsulating medium at all times. The general method of preloading theinsulator which was described in Fig. 7 can be applied to the insulatorshown in 'thru the Fig. 8. However, the ension member is in the form ofa clevis having ears 6. A pin 51 passes ears it and engages theinsulating links ill and I4. Tension is applied to the draw clevis IIbefore the terminal eye I is screwed in place, after which the nut 59may be tightened and the terminal bolt ll screwed into position. Afilling plug I is provided for the expansion chamber.

,Where high strengths are desired a single insulating link may becomequite thick and dimcult to form and cure. member may be made up of twolinks 53 and N. A c section thru the insulating sleeve 52 and the 53 and54 is shown in Fig. 9. The link 4 is made so that it can be slipped overthe link 53. The links are held at oneend by a pin I which is elongatedin cross section. This pin bears against the terminal head 02 and issealed in by a plug 83. The elongated or oval shape of the pin 8|provides stiffness even though the space between the sides of theinsulating link I! is relatively small.

In order to provide an eilicient insulator the insulating link must beof small size and have high strength for a given cross section, and mustbe easily formed. In order to provide an emcient tension member a designbeen developed which will meet the various conditlonsverysatisfactorily. Insulating links embodying the above advantages can-bemade up in several different ways. A very satisfactory link is one madeof canvas or fabric treated with a phenolic condensation product wellknown in the art by the trade name Bakelite. The style of ink used hasthe advantage that links of various lengths can be readily made withoutbeing limited as to the width of the fabric. In order to form the linkstreated fabric of any desired width is wound over flat mandrels whilebeing subject to heat and tension. After the mandrels are covered to thedesired thickness they are placed in a vulcanizing or treating presswhere they are cured.

Such an arrangement is shown in Fig. in which the fabric M tobe treatedis wound on a mandrel I. The mandrel is provided with pins I whichengage driving mechanism so that the fabric under tension.

fabric can be wound onto the mandrel under If desired the mandrel may bemade in parts with joints at '1 so that various lengths of links can bemade by simply using the different lengths of mandrel between thecarefully formed ends. The mandrel 68 is equipped with separableends I!and springs ll which place the tension while being treated. The platensII, II and I3 are heated and the rams 14 subject the" fabric to pressurewhile curing. This insures a dense material and binds the various fiberstogether.

An increased strength is obtained by using fabric which has thestrongest threads running lengthwise. This method "of forming linksmakes it possible to use good widths of material to form a wide link.After treating narrow links may be sawed or cut from the wide link. Thisgreatly reduces the caste! producing allink and makes .it possible toobtain a wide range in' the sine and strength with a minimum amount ofequipment. It is'evident that a suitable mandrel may be wrapped with atreated cord. Individual links may be formed by using platens-withsuitable grooves or by placing forms between the platens. This methodmakes it possible to conform more nearly to the shape of the inner Ifdesired the tension of insulating link has surface of the tube. The cordhas to be wound under considerable tension in order to provide a compactmass which will distribute the load between the various cor In Fig.11 asomewhat different form is shown. 5

The insulating sleeve is composed of two members I! and IS. Two rainsheds or shields l1 and II also are used. The tension member is composedof an inner insulating link I9 and an outer insulating link 00. Theinner insulating link bears 10 upon pins ti and 82, and the outerinsulating link bears upon pins 83 and 84. Using separate bearingmembers for the two links reduces the maximum bearing pressure betweenthe pins and f abric, and permits of a larger cross section in thetension members without a reduction in the ultimate strength for a givencross section. The lower head 85 is provided with ears, the constructionbeing similar to that in Fig. 4. The insulator is given an initial loadin the same manner as that of Fig. '7 and Fig. 8. The nut 86 bears upona recess in the weather shed 11. After the insulator is given thedesired loading the clevis or eye 81 is screwed into position. Byplacing some initial pressure between the heads and the insulatingsleeves it is possible to fill the insulators to the desired pointbefore placing them under final tension. In this way any special fillingmeans can be omitted as the insulator can be filled thru the, spacebetween the draw bolt and the cap 11 before the nut 86 is tightened. Ifdesired filling and draining means may be readily applied. In this typeof construction additional weather sheds may be used which will greatlyreduce the leakage loss during rains. weather sheds also can be used toset up a more uniform gradient, as they act as capacitance plates. Forvery high working loads the weather sheds preferably are of metal. Wherethe insulating housing or sleeves are not subject to heavy workingstresses the weather sheds like that shown in It can be formed ofinsulation, thereby adding to the surface insulation of the insulator.Where insulating flanges or weather sheds are used they usually havemuch greater thickness at the point where they are clamped between theadjacent insulating sleeves. This is in order to prevent a dischargeover the inner surface due to the voltage built up over the outside.

Fig. 13 shows a diilerent modification in which the insulating link 88.is surrounded by an insulating member I9 which is provided withpetticoats or weather sheds 90. .The space 91 may be partially filledwith insulating oil or compound I as previously described. The insulatoris provided with a wire groove 92 and holes 93 for attaching a clampwhich will hold' the. conductor in the groove 92. The insulator is givena conical shape so as to provide high strength for side 00 pull wherethe insulator is rigidly mounted by the base 94.

Fig. 14 is a plan looking down on the top of the insulator, and showsthe holes 95 for bolting the base 94. The draw link is similar to 21 inFi 4.

Tension is applied by tightening the nuts 96. The plug 91 is provided sothat the insulator may be filled with insulating oil or compound-. Theuse of an insulating link which is easily and cheaply made and which maybe gripped with interlinked attachments makes it possible to construct anumber of different insulators on a more efficient basis thanheretofore.

In Fig. 15 the insulating link 98 is attached to terminal members usingsomeone of the vari- 1s plates III and H2 is shown in Fig. 18.

one schemes described. Insulating members 09, I and IM are clampedbetween the terminal members I02 and I03. Gaskets or joints are providedbetween the various sections, or the housing may be made in one piece ifdesired. In order to prevent internal discharge Where the oil level doesnot entirely cover the insulating member a pocket I04 lined with aconducting coating may be used to screen the insulating member 98.

In Fig. 16 the general construction is similar to that of Fig. 13 withthe exception that the insulator is provided with ears I05 which areattached to a bracket I08 by a bolt or pin i071. This arrangement allowsthe insulator to swing in the direction of the line, relieving it of alarge portion if not all of the bending moment due to a broken conductoror an unbalanced stress in the conductor I08. At the same time theconstruction provides rigidity so as to prevent side sway of theconductors under transverse wind loads. This type of construction isparticularly applicable to railway work.

Fig. 17 shows an application of the insulating link in the constructionof multiple element post or radio insulators. In this constructioninsulating members I09 and'IIO are gripped between plates III, H2 and II3. A cross section between The several plates are provided with suitablebearlug surfaces and gaskets. Draw clevises or attachments III and I I5are provided so that insulating links IIG can be placed under tension.This clamps the plates and insulating members together, forming sealedin compartments or spaces for the insulating links II6. This method ofconstruction has the advantage that several insulating members maybeused in multiple to provide a high mechanical strength in tension,compression or for bending moment. By reducing the length of theindividual insulating members and using intermediate moment plates ormembers such as II2 the strength of the insulator for a transverse loadapplied at the top is greatly increased. The insulators may be heatedwith a heating element immersed in the filling liquid, or by an outsidecirculating system. Ports I I1 and ;I II provide for a circulation ofthe oil. An additional expansion chamber may be provided as in some ofthe other types so that the space within the insulating sleeves will becompletely filled and a circulation of warm oil can be obtained. Thecirculation of the oil is desirable as it is then possible to warm thesurface of the insulator to removed films of mois-,

ture.

Fig. 19 shows another application of the insulating link. This issimilar to Fig. with the exception that the insulating housing II 9 ismade in a single piece.

In Fig. 20 the conical insulating housing I20 provides rigidity for apost or pillar insulator, where the conductor is mountedabove theinsulator in the wire groove I 2|. The insulator is provided with ametal rain shed or shield I22 which projects well down into the open endof the insulating member I20. The insulating link I23 is attached insidethis projection by a suitable pin I24. The downwardly projecting portionI25 of the member I22 engages an insulating member I26. The object ofthe insulating member I26 is to provide rigidity for the insulator incase that the insulating sleeve I20 is damaged. As

the member I20 usually is made of fragile material this member may bedamaged by shooting or by rocks thrown against the insulator. It

is highly desirable that the insulating member will not drop theconductor, which may be carrying a high voltage. The member I26 hassufficient strength so that the conductor can be sustained where thefragile insulating sleeve is damaged. In the case of pendant orunderhung insulators an additional sleeve is not necessary as the linksare in tension and not subject to bending moment. The intervening spaceis filled with oil, just sufficient space being allowed for expansion.

The various types of the insulators shown are particularly applicablewhere it is desirable to prevent discharges which will cause radiointerference, the electrostatic field due to the construction being veryfavorable to operation at high voltage. The insulators have smallelectrostatic capacity and therefore they are particularly valuable forinstallation in fog districts,

for radio strain insulators and for insulating self-supportingradiators.

Fig. 21 is a section thru Fig. 20 showing the safety sleeve I26.

Other arrangements may be used such as that shown in Fig. 22 in whichthe insulating link is surrounded by a safety member I21 composed ofwood or other suitable material.

Fig, 23 shows an application of an insulating cross arm of the swingingtype. The member I28 is a tension member, and the member I29 normally isin compression but may be thrown in tension. This member being inapproximately horizontal position is provided with an expansion chamberI30. The arms support an insulator string III. The member I29 may beconstructed in several different ways with or without safety compressionmembers.

Fig. 25 shows one construction in which a non-shattering insulatingsleeve I32 is placed between the insulating link I33 and the fragileinsulating member I34.

Fig. 26 shows a section with a different form of safety compressionmember I35 formed of wood or other material. Grooves I36 may be placedin the side into which the tension insulating links can be fitted.

I claim:

1. An insulator comprising a housing of solid insulating material,fittings at each end of said housing, a tension member in the form of aclosed loop of insulating material connecting said fittings, solidinsulating filling within said housing and extending between the arms ofsaid loop in space not occupied by said arms, and a filling liquid orcompound filling remaining space within said housing.

2. An insulator comprising a link of insulating materials, the arms ofthe link being flat bars extending close together and disposed side byside providing a slot therebetween and extending about the ends of thelink to form loops connecting the two arms, and fittings for oppositeends for said link, said fittings comprising keepers extending throughthe slot between said arms and engaging said loops, and attachment meanssecured to said keepers for applying a load to said insulator, said linkbeing formed of fibrous material impregnated with an artificial resinand cured to impart rigidity to said links.

3. An insulator comprising a link of insulating materials, the arms ofthe link being flat bars extending'close together and disposed side byside proiliding a slot therebetween and extending about the ends of thelink to form loops connecting the two arms, and fittings for oppositeends member and a link of non-fragile dielectric material connectingsaid fittings, said link comprising a continuous flat bar formed into aloop, the opposite ends of said loop being disposed adjacent saidfittings, keepers passing through said loop, one at each end thereof,said bar being slotted transversely of said keepers, and eye membersprojecting from said fittings and extending into the slots in said barto engage said keepers and connect said loop with said fittings.

ARTHUR O. AUSTIN.

